1. Field of the Invention
The present invention relates to an ink jet recording material, a process for producing the same and an ink jet recording method using the same. More particularly, the present invention relates to an ink jet recording material having an ink receiving layer capable of recording thereon ink images with excellent gloss and clarity by any of pigment inks and dye inks, and free from generation of a tacky layer on the ink receiving layer surface, a process for producing the same and an ink jet recording method using the same.
2. Description of the Related Art
The ink jet recording system in which an aqueous ink is ejected through fine nozzles toward a recording material to form images on the recording material is advantageous in that the noise of the ink jet recording operation is low, colored images can be easily recorded, the recording can be effected at a high speed and the recording apparatus is cheaper than other printing apparatuses. Therefore, the ink jet recording system is widely utilized in terminal printers, facsimile machines and plotter machines and for printing account books and slips.
Hitherto, woodfree paper sheets improved in ink absorption and coated paper sheets having a surface coated with a porous pigments have been used as ink jet recording sheets. These conventional ink jet recording sheets have a low surface gloss and thus a mat-like appearance. However, with rapid popularization of the ink jet printer, and enhancement in quality and full coloration of the ink jet images, the ink jet recording material is required to have a high surface gloss, a high image quality, and a high color density of the images. For example, a gloss and image quality similar to those of silver salt photography are required. Also, since all of the above-mentioned conventional recording sheets are opaque and even when a support having a high surface gloss or a transparent support is employed, the coating layer formed on the support is opaque, a recording sheet having satisfactory gloss and transparency cannot be obtained. Accordingly, to provide an ink jet recording sheet having an enhanced transparency or gloss, an attempt has been made to form an ink receiving layer from a hydrophilic polymeric resin selected from, for example, starch, water-soluble cellulose derivatives, polyvinyl alcohol, and polyvinyl pyrrolidone, on a paper sheet or a plastic film. The cellulose derivatives include hydroxypropylmethylcellulose, methylcellulose, carboxymethylcellulose, hydroxypropylcellulose and hydroxyethylcellulose, as disclosed in Japanese Unexamined Patent Publication No. 56-080489, No. 63-160,875 and No. 3-69,388.
On other hand, in a conventional ink jet recording sheet having an ink receiving layer comprising, as a principal component, a porous pigment, to prevent the blotting of the ink in the boundaries between the images and to improve the water resistance of the printed dyes, it is generally known to add various cationic resins, for example, polyamines, polyethyleneimines, dicyandiamide condensation products, and quaternary ammonium salt compounds having a specific chemical structure to the ink receiving layer (coating layer), as shown, for example, by Japanese Unexamined Patent Publication No. 56-84,992, No. 60-161,188, No. 61-293,886 and No. 6-92,012.
As disclosed in Japanese Unexamined Patent Publication No. 63-160,875 and Japanese Unexamined Utility Model Publication No. 60-96,069, even in the ink receiving layer containing, as a principal component, cellulose derivatives, the water-resistance of the ink receiving layer can be enhanced by addition of the cationic resin. However, the increase in an amount of the cationic resin added to the ink receiving layer causes an increase in tackiness of the surface of the ink receiving layer and a decrease in drying rate of the ink printed on the receiving layer.
Japanese Unexamined Patent Publication No. 7-144,466 discloses an ink receiving layer formed from a coating liquid comprising, as a principal component, carboxymethylcellulose. However, the resultant ink receiving layer is unsatisfactory in the quality of images and water-resistance of the ink-receiving layer. Also, the coating liquid is poor in coating property and the resultant coating layer (ink receiving layer) is unsatisfactory in appearance.
Currently, the ink jet recording system is used as a large size graphic outlet apparatus, and the demand thereof in uses such as exterior and interior posters and signboards, and POP advertisements, is rapidly increasing.
In the conventional system, the coloring material comprising an aqueous dye ink having a high coloring property is usually employed. Also, an aqueous pigment ink having excellent light fastness has been developed and is now used in practice.
Japanese Unexamined Patent Publication No. 60-262,685, No. 63-191,670, No. 1-502,805 and No. 8-324,103 and Japanese PCT Publication No. 1-502,805 disclose ink jet recording materials having a ink-receiving layer comprising, as a principal component, a water soluble cellulose derivative, for example, hydroxyethylcelluloes, carboxymethylcellulose, hydroxypropylcellulose, etc. In these ink jet recording materials, since the ink receiving layer is transparent, the resultant ink images have excellent transparency and gloss. However, the drying rate of the ink on the receiving layer is low, and thus the printed surface of the ink receiving layer is kept in wetted and tacky condition for a long time and thus is difficult to handle. Also, when the printing is carried out by using an aqueous pigment ink, the ink receiving layer swells with the aqueous ink and thus the ink images printed on the ink receiving layer are cracked. The cracking refers to a phenomenon of cracking of the ink images comprising a coloring pigment, as a coloring material, when fixed on the ink receiving layer. The size of the cracks are relatively small but the cracks can be observed by the naked eye and cause the color density of the ink images to be uneven. This image cracking phenomenon is significantly found in color-mixed images which comprise two or more inks different in color from each other in a large amount. As a result, the cracks formed in the ink images cause the ink images to exhibit low color density and gloss, and thus to be unclear.
To solve the problem of the wetting and tacky condition of the printed ink images, Japanese Unexamined Patent Publication No. 61-74,879 discloses an ink receiving layer comprising an ethylene oxide polymer. In this type of the ink receiving layer, the wetted and tacky condition of the printed ink images can be solved. However, when the aqueous dye ink is used, this type of the ink receiving layer is disadvantageous in that the printed ink images exhibit a reduced gloss, the printed ink diffuses into the ink receiving layer with the lapse of time, and thus the resultant ink images are unsuitable for records which must be stored for a long period of time.
Also, this type of ink receiving layer exhibits a non-improved resistance to the image-cracking problem when the aqueous pigment ink is employed. Thus, on the pigment ink images formed on this type of ink receiving layer, cracking occurs.
To solve the cracking problem of the aqueous pigment ink images, Japanese Unexamined Patent Publication No. 10-67,168 provides an ink jet recording material having an ink receiving layer which comprises a binder and silica sol particles or alumina sol particles having an average particle size of 20 to 200 nm and exhibit a high transparency. In this type of ink jet recording material, since the ink is absorbed in fine pores formed between the fine pigment particles, there is a tendency that the swelling of the ink receiving layer by the ink is small, and the resistance of the aqueous pigment ink images printed on the ink-receiving layer to cracking is enhanced. However, the ink receiving layer per se has a tendency that during a drying procedure of the coating liquid layer for the ink receiving layer, the resultant ink receiving layer is cracked and exhibits a reduced transparency.
When the content of the binder is increased for the purpose of preventing the cracking of the ink receiving layer, the size of the pores formed between the pigment particles decreases. Therefore, to prevent the cracking of the ink receiving layer, the amount of the ink receiving layer should be increased. The increased amount of the ink receiving layer causes a reduced transparency of the resultant ink receiving layer. Also, a decrease in the ink-absorbing rate of the resultant ink receiving layer and an increase in the ease of the ink-diffusion into the ink receiving layer, occur, and it becomes difficult to balance the various properties of the ink receiving layer. Further, this type of ink receiving layer has an insufficient level of resistance to cracking of the aqueous pigment ink images formed thereon.